Journals that are only published online and are not part of PMC, PubMed or any other database do not always display the citation pieces in a obvious way. Here are a few tips for locating the citation pieces.
RDH (Registered Dental Hygienist) magazine is freely available on the Internet at http://www.rdhmag.com.
When you view an article from this journal, the volume and the issue are not displayed with the article. You will see the article title, the author, and the date of the journal. To find the volume and issue, look at the url:
http://www.rdhmag.com/articles/print/volume-37/issue-7/contents/the-inevitability-of-change.html
In this example the volume is 37 and the issue is 7.
For articles without page numbers:
If the article is printed out, count the number of pages, and add the word about in square brackets to the total number of pages.
For example: [about 10 p.].
PLOS ONE
It does not list the volume, issue, or pages in the results entry.
In the opened entry of the article, click on: 
When the article opens, look on page one for the section on the left that says OPEN ACCESS and citation.
The volume is 11 and the issue is 12. The article itself has 15 total pages so a completed citation for this article is
Volgenant CM, Hoogenkamp MA, Krom BP, et al. Red and green fluorescence from oral biofilms. PLoS ONE [Internet]. 2016 [cited 2017 Jul 31;11(12):15 p. Available from: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0168428&type=printable